This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of VETSA is to quantify the genetic and environmental influences on age-related cognitive changes in mid-life. Wave 1 of data collection (VETSA 1) began in 2002 and resulted in the successful assessment 1,237 participants with data collection ending in October 2007. VETSA 2 has the following aims and hypotheses. Aim 1. Completion of VETSA 1 baseline assessment: During the first year of the project we will assess new twin pairs in order to bring the sample size for the baseline assessment begun in VETSA 1 to the targeted 1440. This will allow for greater statistical power in future longitudinal analyses. Aim 2. Characterize genetic and environmental influences on cognitive change over time: This Aim will yield answers to the following questions: a) To what extent are genetic and environmental factors responsible for individual trajectories of change in general cognitive ability across adulthood (from age 20 to 65)? b) To what degree do specific cognitive processes change during late middle age? c) To what extent are observed changes in different cognitive domains correlated due to shared genetic or environmental effects? d) To what extent do the components of processing speed and working memory predict changes in cognitive performance?